There are several elements here that have to do with culture and pathology. First, the differences between cultures. Although you haven’t said it my guess is that your husband comes from a different culture than you’ve been raised in. In some cultures giving up the marital bed when the parent comes to visit is customary — as is having children sleep in the same bed with a parent. In fact, it may be a sign of disrespect to have children sleep apart from the parents as is noted in this terrific article on differences in culture with regard to sleeping customs.
But this does not account for your husband’s choosing to sleep in his mother’s bed at 36 and giving up the marital bed without conferring with you. There are anomalies here for sure. They may have had innocent enough beginnings, but now they have dire consequences with regard to the marriage.
I recommend you talk directly to your husband about your needs. Explain that a grown man sleeping with his mother is something that is difficult for you to accept, and giving up the marital bed when his mom comes to visit isn’t agreeable. Talk to him directly about what your feelings and needs are and hear what he has to say. Explain that the boundaries and feelings of being in competition with his mother are very real and that you do not want to keep feeling them without expressing them. It is time to speak up. Not an attack, but an expression of what you are uncomfortable with. Ask for his help in changing these things.
If that doesn’t work I would highly recommend a few sessions with a couples therapist to sort through the issues. You can find someone at the top of the page on the “Find help” tab or a qualified therapist here.
Wishing you patience and peace,
Proof Positive Blog @ PsychCentral